There are a broad range of application-specific needs for lighting and display technologies used in homes, workplaces and consumer products. Precise control of the output spectrum of lighting products is desirable to match the requirements for color temperature and output directionality, while at the same time optimizing power efficiency and manufacturing cost. See U.S. Pat. No. 8,692,446 and US 2013/0051032. For video display applications, controlling the blend of primary colors in each pixel is necessary, while the control of pixel output directionality must be tailored for a range of viewing methods that may be either tightly confined (for privacy) or widely dispersed (for wide viewing angle).
By varying the duty cycle, period, and refractive index, the resonant characteristics of photonic crystal (PC) structures can be tuned to interact with wavelengths extending from the ultraviolet to the infrared. Certain photonic crystal structures have been used for a variety of applications including polarizers, filters, biosensors, optical communication components, displays, and lighting, PCs have been incorporated into light emitting diodes (LEDs) in order to increase extraction efficiency, and to control the directionality of light output, either normal to the device or into angular sidelobes.
While certain photonic crystal structures have been reported, improved light-emitting structures are needed for many applications.